The various devices that constitute a storage system, for example disk drives and host computing systems, are commonly interconnected via a high speed serial channel technology known as Fibre Channel arbitrated loop. Copper cables can be used to interconnect Fibre Channel devices that are relatively close together. However, copper cables are not capable of transmitting the high speed signals more than a few tens of meters. So, in order to connect, for example, a host system Fibre Channel interface to a Fibre Channel storage system in another room, an optical cable is used. Optical cables are capable of transmitting the high speed signals hundreds of meters.
Copper cables and optical cables use different, incompatible connectors. Storage devices should preferentially support either type of connector, since a given customer's requirements are not known. One way to do so is to produce two different storage devices—one with a copper connector, and one with an optical connector. This solution is disadvantageous in that two separate devices need to be manufactured and supported, and customers have limited flexibility in the arrangement of their systems once the devices have been purchased. Another solution involves the use of an optical cable adapter that plugs into the copper connector. However, these adapters have been found to be unreliable. In addition, special cables are required when using these adapters, forcing the customer to purchase more components and again limiting flexibility. Furthermore, many storage devices are already configured to support copper connectors. In order to modify the storage device to support an optical connector, hardware and software changes must be made so that the processor in the storage device can control the optical cable connection. This disadvantageously results in the need to produce and maintain two different software bases—one for the device that supports the copper connector, and another for the device that additionally supports the optical connector.
What is needed is a way to provide a storage device capable of supporting either copper or optical connections, such that different types of devices need not be manufactured, and such that a device that supports a copper connector can be modified to support an optical connector without the need for any software changes.